SOLUTION: If the sides of a square are decreased by 3 cm, the area is decreased by 81cm^2. What were the dimensions of the original square?

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: If the sides of a square are decreased by 3 cm, the area is decreased by 81cm^2. What were the dimensions of the original square?      Log On


   

Question 52026This question is from textbook Beginning Algebra
: If the sides of a square are decreased by 3 cm, the area is decreased by 81cm^2. What were the dimensions of the original square? This question is from textbook Beginning Algebra

Answer by mathchemprofessor(65) About Me  (Show Source):
You can put this solution on YOUR website!
Let the original sides fo the square be xcm
Area of the square= x^2 cm^2
When the sides are decreased by 3cm, then the area is (x-3)^2 sq cm
Given:
x^2-(x-3)^2=81
x^2-(x^2-6x+9)=81
x^2-x^2+6x-9=81
6x=81+9=90
x=15
So, the original dimensions of the square=15cm